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Old 08-27-2005, 11:43 AM   #81
vaio76109
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Well larger rotors cant fit the stock caliper so the caliper would have to moven out via different mounts.
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Old 08-27-2005, 01:35 PM   #82
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Quote:
Originally Posted by vaio76109
Well larger rotors cant fit the stock caliper so the caliper would have to moven out via different mounts.
Depends on the car. There are cars where you can fit larger rotors on and still clear the calipers (without needing to move them). Granted, not signifigantly larger, but larger still.

Also, there are cars where people can do that and then relocate their stock calipers to use a slightly larger pad.

Keep in mind that anyone just searching Google on brake upgrades may run across this thread. It has concepts that apply to ALL cars.
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Old 09-17-2005, 04:45 PM   #83
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Quote:
Originally Posted by gbn
I have a '02 325i with sport package. I have Axxis Metal Master pads and need new rotors. I can't afford a big brake kit but would like to have a little more stopping power. The OEM rotors were ok. I've done a little research into slotted, cross drilled (staying away from them), frozen and combinations.
What do you plan to do with this car? Do you autocross it? Take it to high speed driving events? Or is this just a daily driver? How important is brake dust?

What did you not like about the stock brakes and Metal Master pads? Did you ever fade them? What does "stoppping power" mean to you? What kind of tires (make & model) do you have?
Quote:
Anybody have any "real" test data with stopping distances? If not do the frozen rotors really last 2 to 3 times as long?
The claims made by companies that cryo-temper rotors are completely false. They do not last 3 times longer, nor do they operate at lower temperatures. What you will never see from this industry is a double-blind test that uses the scientific method to demonstrate the benefits of frozen rotors. Instead, you'll hear wild claims from race drivers who are getting their rotors free and will say anything to keep the free stuff coming. If you have some money to blow, you could always purchase a complete set of rotors, have one front and one rear rotor cryo-tempered and have someone install them, but not tell you which was which. Have them seal this information in an envelope. If you go to the track or autocross, you could use a pyrometer to see if one side or the other was consistantly cooler than the other. And after a few thousand miles, you could use a micrometer to see if one side was wearing two or three times faster than the other. Finally, you could open the envelope to see if the results corresponded to the vendors' claims. I'm willing to bet they won't.
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Old 09-17-2005, 05:09 PM   #84
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Quote:
Originally Posted by rnitti
Hawh HPS pads are NOT designed for track use. The HP are.
HP Plus pads are not appropriate for the race track. They are ideal autocross pads with incredible cold bite - better than almost any other street pad. Their tendency to squeal under light braking and their moderately aggressive rotor wear and dust prevents many people from running them all the time on the street. But you should not take them to the track. The problem with HP Plus is not a tendency to fade. Their MOT is higher than HPS and most other street pads. However, once you reach MOT, they fade almost completely and without warning. If you look at the friction vs temperature curve of these pads, they seem to fall off a cliff when you reach MOT. That's not what you want on the track. You want a pad that gradually loses friction after reaching MOT, giving you enough warning to manage your brakes. With HP Plus, you could have fantastic brakes for laps 1-4 and then have nothing in lap 5. No warning. You're off the track, hopefully into an area with lots of runout. I've had at least four customers report to me that this is exactly what happened to them when running HP Plus. And while at a brake friction seminar last July, taught by Rob Nelson - former President of Hawk's friction division, he told us to NEVER let our customers run HPS or HP Plus at the track for this very reason. If the president of the company that makes the pads tells me they aren't appropriate for the track, I tend to believe him. And his information was corroborated by my customers.
Quote:
Slotted rotors are nice. They will help disapate gasses between the pad and rotor which does decrease stopping distance, but you're only talking a few feet at 60mph. Slotting also helps to disapate water off of the disc in the rain. Drilled rotors are more for looks than real benefit IMO. They are also more prone to cracking.
Slotted rotors offer improved initial bite over plain rotors. Drilled can be shown on a brake dyno to offer slightly more bite, but it's barely noticeable by a human. Drilled rotors also shave off 1/4 to 1/2 pound of weight per rotor, which can make a difference in a close race. The cracking problem is limited to track use. For track, I strongly suggest slotted rotors. For the street, it's up to you. Unless you have counterfeit Brembo rotors from eBay, you shouldn't run into any problems with drilled rotors cracking under typical street driving.
Quote:
Larger brake kits decrease stopping distance in two ways: First, the amount of brake pad and rotor area is increased which increase the amount of area that the pads and rotors contact each other, hence, more friction.
The coefficient of friction between a pad and a rotor is independent of the amount of surface area. Otherwise, pad vendors would need to specify a different Cf for each pad shape! Similarly, the area of contact between a pad and a rotor does not enter into the amount of torque generated by the brakes. The brake torque equation is: Torque = Effective Radius x Clamping Force x Coefficient of Friction

Since coefficient of friction is not a function of pad surface area, then brake torque is not a function of pad surface area.

Big brakes reduce stopping distance the following ways:

In a fade limited situation (i.e., the race track), the higher thermal capacity of a big brake system allows you to brake consistently from lap one to lap thirty.

In a panic stop, a big brake system with fixed, multi-piston calipers can reduce your reaction time. The delay from when you hit the brake pedal to when actual braking starts to occur can be reduced and the reduction in stopping distance is a function of that reduction in delay and the initial speed when you hit the brakes. For example, your car travels 21 feet in 2 tenths of a second at 70 mph.
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Old 09-17-2005, 05:20 PM   #85
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Originally Posted by Asmodeus
Race Pads stop the car faster than street pad simply because the pad compound has a higher coeficient of friction.

Higher friction = stop 'faster' = shorter lifetime
Race pads do not stop the car faster due to higher friction. They allow the race driver to consistantly take advantage of the tire's capability without having to worry about pad fade. A street pad will stop a car in the same distance as a track pad up until the point at which the street pad exceeds its maximum operating temperature. From that point on, the race pad will work better. Most street pads have an MOT in the range of 800 degrees F. In contrast, the Performance Friction 01 race pads have an MOT of 2,000 degrees F.

In a side-by-side comparison of single-stop distance from 60 to 0 mph, there will be no difference between race pads and street pads. The higher Cf race pads will require less pedal pressure from the driver to reach the point of threshold braking or ABS intervention. But the stopping distance will be the same. You are tire limited in a cold stop. Running race pads in the street will not result in a shorter stopping distance in a panic stop.
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Old 09-17-2005, 05:27 PM   #86
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Quote:
Originally Posted by Asmodeus
I know the argument for slotting rotors, but i don't think we are using pads that require them.
No pads "require" the use of slotted rotors. Slotted rotors offer the benefit of increased initial bite as well as giving the boundary layer of gasses and particles a place to go. They also maintain a fresh surface on the pads, eliminating pad glazing in exchange for a very minor penalty in pad life. Slotted rotors can provide these benefits, regardless of the pads you use on the track or on the street.
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Old 09-17-2005, 05:36 PM   #87
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Quote:
Originally Posted by gbn
Regarding BBK's I agree about the force, friction coefficent, heat build-up, rotor size and racing vs. street pad issues. Good point about the brake porportioning. Most BBk's have 4 piston calipers, vs. 2 piston OEM. Other than more even braking force, does anyone know why they do it?
Actually, most OEM calipers have only 1 piston. The entire caliper slides back and forth on a couple of steel guide bolts. They do this for a number of reasons. The calipers are much less expensive to manufacture. And the lack of a piston on the outboard side allows for better wheel clearance. This is why many multi-piston big brake kits require wheel spacers to create enough room behind the spokes for the additional caliper width.

4-piston, 6-piston, and even 8-piston calipers are designed to allow the use of wider pads. Single piston floating and 2-piston opposed calipers usually are loaded with pads that are almost square in cross section. For example, here's the pad shape used in the StopTech ST22 caliper (and Nissan 350Z Track Model with Brembo calipers):




Compare this to the wider pad used in the ST60 6-piston caliper:



You can see that a single piston would not work on the wider pad.
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Old 09-17-2005, 05:55 PM   #88
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Originally Posted by Mr Paddle.Shift
So for HT-10, I could technically change it the day before the event. Drive up to the event. Finish the event. Drive home and change back to HP Plus?
In fact, you want to do exactly that. When cold, the HT10 pads will completely polish away the old transfer layer from your street pads. When you reach the track, bed them in and then have at it! After the event is over, leave the HT10 pads installed for your drive home. By the time you get home, the HT10 pads will have polished away their own transfer layer, leaving you nice clean rotors upon which to re-bed your street pads.

This technique eliminates the judder problems that are common when track pads are bedded directly on top of the street pad transfer layer. I've even written an article about this: http://www.zeckhausen.com/avoiding_brake_judder.htm
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Old 09-17-2005, 08:49 PM   #89
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Originally Posted by DZeckhausen
In a side-by-side comparison of single-stop distance from 60 to 0 mph, there will be no difference between race pads and street pads. .

I disagree because i have done numerous 150-30 km/h (sorry, don't feel like converting to mph) 'stops' at the track where I go lapping every week, and the HP+ require a much shorter distance than the HPS.

Friends of mine have tried the Gransport GS3 and all agree that the stopping distance is less than with the HP+ which is less than the HPS.

In coefficient of friction comparisons. GS3 > HP+ > HPS.

Don't mean to be a pain in the ass, but what you are saying contradicts what we experience at the track every week. Unless if I am not understanding you correctly.
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Old 09-18-2005, 06:55 AM   #90
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Quote:
Originally Posted by Asmodeus
I disagree because i have done numerous 150-30 km/h (sorry, don't feel like converting to mph) 'stops' at the track where I go lapping every week, and the HP+ require a much shorter distance than the HPS.

Friends of mine have tried the Gransport GS3 and all agree that the stopping distance is less than with the HP+ which is less than the HPS.

In coefficient of friction comparisons. GS3 > HP+ > HPS.

Don't mean to be a pain in the ass, but what you are saying contradicts what we experience at the track every week. Unless if I am not understanding you correctly.
That's because the HPS are quickly fade limited at the track, whereas the HP Plus (under the conditions imposed by your skill and equipment level) are not. If you read my post carefully, I'm saying that there will be no difference in stopping distance between a street and race pad during a single stop comparison. Under those conditions, you are not fade limited. When you are not fade limited, you are always tire limited.

I should probably add one more caveat. If, during that single stop comparison, the race pads heat up enough to get into their operating zone, you may end up having to lift off the brake pedal slightly to avoid locking up the wheels or engaging ABS. Unlike street pads, which tend to have a flat torque curve when cold and then lose friction when MOT is exceeded, race pads have a lower friciton level (often until about 300-400 degrees F) and then suddenly jump up to a higher friction level. You can feel this when bedding them in, usually on the 3rd or 4th slowdown. It feels like someone flipped the "power brakes" switch.

Getting back to the HP Plus pads, I urge you to swap them out (for track use) for either a true race pad or a street pad that doesn't have such a dangerous slope to the friction vs temperature curve. You apparently haven't bumped up against the HP Plus pads' MOT yet, but as you continue to improve your skills and your equipment level, you will eventually. At that time, you may find yourself up against a tire barrier or at least deep in gravel, picking stones out from between your tire sidewalls and the tire beads.
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Old 09-18-2005, 07:40 AM   #91
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Dave, excellent info, thanks.

So what do you recommend for brake pads that offers same or better than OEM braking for the street-that gives off less brake dust than OEM?

I currently have the Axxis delux plus on my vehicle (330ci). I am impressed with the less dust. I would say they dust 95% less than OEM. However, more importantly the braking power is much less. This I don't like at all. I read alot of post that said they were almost the same that the axxis were just a little less than OEM in braking power. To me, I would keep the dust over the stopping power.

I recently had the opportunity to drive a 2005 330i as a loaner for 4 days. Bottom line is I want that stopping power back!!!!! I miss the ability to stop on a dime feeling. I also autox and definitely miss the braking power!!!
help.
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Old 09-18-2005, 01:38 PM   #92
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Quote:
Originally Posted by DZeckhausen
What do you plan to do with this car? Do you autocross it? Take it to high speed driving events? Or is this just a daily driver? How important is brake dust?
I autocross, but it's also a daily driver. Brake dust is not too important to me, but I have to admit that the Metal Masters have a lot lest dust, which I kinda like (a bonus?). Not into high speed or track stuff yet (insurance!).

Quote:
Originally Posted by DZeckhausen
What did you not like about the stock brakes and Metal Master pads? Did you ever fade them? What does "stoppping power" mean to you? What kind of tires (make & model) do you have?The claims made by companies that cryo-temper rotors are completely false. They do not last 3 times longer, nor do they operate at lower temperatures. What you will never see from this industry is a double-blind test that uses the scientific method to demonstrate the benefits of frozen rotors. Instead, you'll hear wild claims from race drivers who are getting their rotors free and will say anything to keep the free stuff coming. If you have some money to blow, you could always purchase a complete set of rotors, have one front and one rear rotor cryo-tempered and have someone install them, but not tell you which was which. Have them seal this information in an envelope. If you go to the track or autocross, you could use a pyrometer to see if one side or the other was consistantly cooler than the other. And after a few thousand miles, you could use a micrometer to see if one side was wearing two or three times faster than the other. Finally, you could open the envelope to see if the results corresponded to the vendors' claims. I'm willing to bet they won't.
I've already bought the plain cryo rotors (no slotting or drilling). So I'll just have to make my own opinion about rotor life. If I don't see anything significant longevity then it's back to OEM, maybe slotted, next time. I did notice that during some highway driving the OEM pads would fade during hard braking above 60 mph or so. The Metal Masters don't seem to fade until much higher speeds (well over 80 mph), but they seem to have less bite during lower speeds when cold. So, I'm thinking that they are not the best choice for an autocross pad. For next time what pads would you recommend for a daily driver that you autocross? You seem to be a dealer of some sort. I currently have Kumho Ecsta MX on my 2002 325i with sport package. I wonder if someone could convince TireRack to do some brake testing? They test tires don't they...
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Old 09-20-2005, 04:28 PM   #93
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Quote:
Originally Posted by gbn
I autocross, but it's also a daily driver. Brake dust is not too important to me, ...{stuff deleted}...

For next time what pads would you recommend for a daily driver that you autocross?
That's pretty easy. The Axxis Ultimate will give you better cold bite and much greater resistance to fade, as well as excellent pedal feel. More dust than D+ and XBG (formerly Metal Master) but less dust than stock. Be sure to bed them in properly per: http://www.zeckhausen.com/bedding_in_brakes.htm

If they didn't make so much darned noise and produce so much dust, I would suggest the Hawk HP Plus. They really do have excellent bite. But I don't consider them livable for daily driving in a car that might end up in valet parking outside a fancy restaurant or in front of the country club, dropping off folks to a black tie ball.
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Old 09-20-2005, 11:50 PM   #94
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Originally Posted by DZeckhausen
But I don't consider them livable for daily driving in a car that might end up in valet parking...
Funny you should mention that. I have HP+ on my car and I can tolerate the screeching, it's the howling that I hate. Lately the rears have been howling LOUDLY. People in other cars think that they're under attack. So last week when I had to have my car valet parked, I felt obligated to inform the valet that the car would stop wonderfully and that the noise was no cause for concern.
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Old 09-23-2005, 12:22 PM   #95
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pads

Has anyone tried the Ferroda 2500's? I just did my first track event at Watkins Glen and the only issue I had was brake fade with the stock pads.
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Old 09-24-2005, 10:07 AM   #96
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Originally Posted by tuckersmg
Has anyone tried the Ferroda 2500's? I just did my first track event at Watkins Glen and the only issue I had was brake fade with the stock pads.
While the Ferodo DS2500 pad would be an improvement over the stock pads, they would probably not be ideal. I would expect them to be consumed relatively rapidly in the front calipers of an E46 M3.

If you want a pad that is going to last a very long time, you might try the Performance Friction 97 (PFC97). Most people eventually end up with the PFC01 pads because they love the more aggressive bite and absolute consistency, even at the advanced levels with R-compound tires. But if you're just starting out, the PFC97 may be a better choice, since it's easier for a novice to modulate. And it's certainly more economical, given its long life.

PFC97 is also a good rain pad for those who normally use PFC01 in front. The drop in Cf helps the rear brakes do a greater percentage of the (reduced) total work on a slippery track.

All of these pads are race-only and should be swapped with street pads for normal (non-track) driving. Follow these guidelines when swapping to avoid judder problems: http://www.zeckhausen.com/avoiding_brake_judder.htm
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Old 10-01-2005, 09:28 AM   #97
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Brake bedding

I took the advise regarding bedding brakes this morning. I found an empty industrial subdivision at about 6 am. Got up to about 60 mph and hard braked, not panic braking, to about 15 mph about 8-9 times. There was definitely smoke and a strong brake smell. I ran about 15 minutes barely touching the brakes at all and mostly cruising at 40-60 mph. There is still some brake dust smell, but the brakes seem to bite much better now. I've got an autocross tomorrow and will comment back on the changes.

I finally got my car back from the body shop yesterday. They did a nice job cleaning the wheels. It looks like I haven't washed the wheels in about 2 weeks now!
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Old 10-05-2005, 07:16 PM   #98
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Yeah let me just add... the stock 325 brakes are pure crap. My car is at 18000 miles, and the brakes are completely shot. The front right rotor cracked from just 3 hard stops one day which where about 3 mins apart. I can't wait to get a BBK; if they were only more affordable...
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Old 10-20-2005, 03:27 PM   #99
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Brake bedding

My autocross went fine. My lap times were good, but I hit too many cones to get a trophy! Anyway, the brakes worked well during the autocross, but afterwards on the way home they started squeeking pretty bad again on soft stops. Oh well, at least pedal feel is still pretty good.
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Old 10-20-2005, 03:31 PM   #100
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brakes dont get too hot during an auto-x, its mainly track events that they do.
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